1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the same, and more particularly, it relates to a semiconductor device comprising an interlayer dielectric film and a method of fabricating the same.
2. Description of the Background Art
A porous interlayer dielectric film is generally known as a film isolating conductive layers of a semiconductor device from each other, as disclosed in Japanese Patent Laying-Open No. 2005-272188, for example. In the semiconductor device employing the porous interlayer dielectric film disclosed in the aforementioned Japanese Patent Laying-Open No. 2005-272188, the dielectric constant of the interlayer dielectric film can be so reduced as to reduce a parasitic capacitance between wires.
A structure of a semiconductor device having an SiO2 or SiN film formed on an interlayer dielectric film is also known in general. When a wiring layer is formed on the interlayer dielectric film and the surface thereof is flattened by partially polishing the wiring layer by CMP (chemical mechanical polishing), the SiO2 or SiN film formed on the interlayer dielectric film functions as a CMP stopper.
In the conventional semiconductor device employing the porous interlayer dielectric film, however, a large quantity of hydrophobic groups such as methyl groups disappear from the interlayer dielectric film when a wet process using a liquid such as a chemical solution or a plasma process is-employed in any step of preparing the semiconductor device, to disadvantageously increase hygroscopicity of the interlayer dielectric film. Consequently, the liquid such as a chemical solution easily penetrates into the interlayer dielectric film, to disadvantageously deteriorate the interlayer dielectric film.
When the interlayer dielectric film of the conventional semiconductor device having the SiO2 (SiN) film formed thereon is exposed to a prescribed gas atmosphere for recovering the interlayer dielectric film from deterioration, on the other hand, the SiO2 (SiN) film disadvantageously inhibits the prescribed gas from penetrating into the interlayer dielectric film. Consequently, it is difficult to recover the interlayer dielectric film from deterioration with the prescribed gas.